Slide projectors of this type are frequently used in slide presentations, the lecturer controlling the projector functions by means of a remote control device which may be connected to the projector via a cable. Cable-less remote control devices which include an IC transmitter are however also known, an IR receiver being arranged on the projector and transmission of the control signals being effected optically in the IR range. The various control signals are all encoded accordingly and evaluated, i.e. decoded, in the projector and associated with the respective functions.
During such presentations it may occur that the lecturer wishes to interrupt the performance to give additional explanations on a blackboard or show some objects. As in most cases the slide projector is placed in the back of the room and the lecturer stands in front of the audience near the screen, a second person would have to switch the projector off and, when the slide presentation is to be continued, on again. This may be quite disruptive, in particular if still a third person is desired to turn the room light on and off.
As a result, it would be desirable that the lecturer himself can switch on and off the projector as required by using his remote control device.